Related Experiment Video

Updated: Nov 16, 2025

Isolation of Human Atrial Myocytes for Simultaneous Measurements of Ca2+ Transients and Membrane Currents
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Isolation of Human Atrial Myocytes for Simultaneous Measurements of Ca2+ Transients and Membrane Currents

Published on: July 3, 2013

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Routine Measurement of Thyroid Stimulating Hormone in Patients Presenting With Third-Degree Atrioventricular Block:

Muhammad Faisal1, Zubair Mumtaz1, Abdul Mueed1

  • 1Electrophysiology, National Institute of Cardiovascular Diseases, Karachi, PAK.

Cureus
|February 22, 2021
PubMed

Insights

Thyroid dysfunction is rare in patients with complete heart block (CHB) and no apparent hypothyroidism symptoms. Routine thyroid testing in these cases may not be necessary, suggesting cautious prescription of thyroid screening.

Area of Science:

  • Cardiology
  • Endocrinology
  • Internal Medicine

Background:

  • Hypothyroidism can cause sinus bradycardia.
  • Thyroid testing is often routine in complete heart block (CHB) patients, despite limited supporting data.
  • The necessity of thyroid evaluation in CHB without clinical hypothyroidism requires investigation.

Purpose of the Study:

  • To determine the frequency of thyroid dysfunction in patients presenting with CHB.
  • To assess the utility of routine thyroid screening in CHB patients without overt hypothyroid symptoms.

Main Methods:

  • Cross-sectional study including 102 patients referred for permanent pacemaker implantation for CHB.
  • Exclusion of patients with known thyroid disorder or clinical features of thyroid disease.
  • Collection of demographic, electrocardiography (EKG), and thyroid-stimulating hormone (TSH) data.

Main Results:

  • Only one patient (less than 1%) out of 102 had an abnormal TSH level.
  • The study population had a mean age of 61.09 years, with common comorbidities like hypertension and diabetes.
  • The mean ventricular escape rate was 36.17 ± 5.93 bpm.

Conclusions:

  • Thyroid dysfunction is infrequent in patients with CHB who do not exhibit clinical signs of hypothyroidism.
  • Routine thyroid screening may be overutilized in clinically euthyroid CHB patients.
  • Clinical judgment should guide thyroid testing in CHB patients.

Keywords:
atrioventricular blockcomplete heart blockpermanent pacemakersthyroid stimulating hormonetsh

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